I read an interesting Rolling Stone article: R.I.P. GOP

His main contention was that the Republican Party has attacked government so much that first The Tea Party and now Trump (a life-long Democrat) are now the result. The working class Republicans have finally turned against establishment career Republicans who promise them everything and then go to Washington and do nothing they promised. If you subtract Trump supporters from the Republican Party, you are left with a small fraction of the once Grand Old Party. Certainly not enough voters to ever win the Presidency again.

In my opinion, they simply don't realize that Trump is more an old-school (pre-Civil Rights Act) Democrat. (Besides being a maniac and totally unqualified for any elected office, of course.)